check_oem_password: incorrect password length (456509439).
Дейтер Александр Валерьевич
tiamat at komi.mts.ru
Wed Oct 1 06:44:12 GMT 2003
> I cannot change user password from Win2k workstations with ctrl+alt+del,
> length of the current password is more than 14 symbols.
I search this topic on google and found this acticle:
With LM, password hashes were split into two separate 7-character hashes.
This actually made passwords more vulnerable because a brute-force attack
could be performed on each half of the password at the same time. So
passwords that were 9 characters long were broken into one 7-character hash
and one 2-character hash. Obviously, cracking a 2-character hash did not
take long, and the 7-character portion could usually be cracked within
hours. Often, the smaller portion could actually be used to assist in the
cracking of the longer portion. Because of this, many security professionals
determined that optimal password lengths were 7 or 14 characters,
corresponding to the two 7-character hashes.
NTLM improved the situation some by using all 14 characters to store the
password hash. While this did make things better, NT dialog boxes still
limited passwords to a maximum of 14 characters; thus the determination that
passwords of exactly 14 characters are the optimal length for the best
But things are different with newer versions of Windows. Windows 2000 and XP
passwords can now be up to 127 characters in length and so 14 characters is
no longer a limit. Furthermore, one little known fact discovered by Urity of
SecurityFriday.com is that if a password is fifteen characters or longer,
Windows does not even store the LanMan hash correctly. This actually
protects you from brute-force attacks against the weak algorithm used in
those hashes. If your password is 15 characters or longer, Windows stores
the constant AAD3B435B51404EEAAD3B435B51404EE as your LM hash, which is
equivalent to a null password. And since your password is obviously not
null, attempts to crack that hash will fail.
I change my password to 'verylongpassword' and check it with pdbedit:
# pdbedit -w -u user
I.e. my Lanman Password Hash = 4781F57DEE2192BC0E10727E7B110A2F
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